Centrifugal separation apparatus



Dec. 6, 1960 2. VANE CENTRIFUGAL SEPARATION APPARATUS 2 Sheets-Sheet 1Filed Jan. 29, 1958 M, INVENTDE' Dec. 6, 1960 2. VANE CENTRIFUGALSEPARATION APPARATUS 2 Sheets-Sheet 2 Filed Jan. 29, 1958 'CENTRIFUGALSEPARATION APPARATUS Zdenek Vane, Box 225, Postal Station D, Ottawa,Ontario, Canada Filed Jan. 29, 1958, Ser. No. 712,000

3 Claims. (Cl. 209-211) This invention relates to improvements incentrifugal separating methods and apparatus, and more particularly tomultiple separations of suspended solid particles by density diflerence.

In the prior art, the starting point for density separations of finesolids is a completely str-atified mixture in a spinning carrier.Generally, the components are separated from the stratified mixture in aradial or axial direction. When the product of separation is to betreated again, as it is necessary for instance to separate an excess ofthe carrier from the solid component, such secondary separation is to beperformed in a new apparatus, or apparatus section. Consequently,conventional apparatus possess little compactness of structure anduniformity of method, and are often a mere aggregation of separators,wherein intermediate steps of evacuating and refeeding, conveying andpropelling the handled materials accom pany a positive separation work.In this invention, spinning particles in suspension are separated outinto concentric layers of different density ranges through the action ofa free vortex of carrier fluid spinning helically, and are interceptedduring their radially outward travel by a system of concentric sleeves.The spin and the radial spreading is continued within said system, thefirst separation being followed by one or several subsequentseparations, using the same primary spin. In this novel method, thestarting point of separation is the discharging of a concentratedseparable material into a spinning column of a pure carrier fluid. Asthe Stratification of the separable mixture proceeds, the resultingdensity layers are. intercepted by separating means. This novel methoddivides. the spinning carrier into layers wherein the separ'ablema-zterial just started to be stratified according to density, and is,therefore, able to operate more economically'by treating one separablecomponent in two or more separation steps performed in the sameseparation chamber while spinning the separable material only once. Inthis invention, the separation of the particles and the evacuation ofthe carrier fluid are performed in a compact structure in the shortestpossible manner, thereby reducing working surfaces in contact with thehandled material, decreasing the time of contact on these surfaces, thussaving in construction material, power of operation, time ofsep-aration,and in wear by abrasion.

It is an object of this invention to provide a novel method andapparatus for multiple separations of suspended particles according todensity by spreading fine solids in a spinning carrier from the centerthereof and by intercepting the carrier with therein suspended solidparticles during its flow in an axial direction by a system ofseparating sleeve partitions.

Another object of the invention is to provide a novel compact separatingstructure allowing for further subseparating the product of the primaryseparation.

Other objects of this invention will become apparent from the followingdescription and accompanying drawings in which t Figure 1 is alongitudinal section of my new apparatus,-

Patented Dec. ti, 1960 Figure 2 shows a horizontal section of the samealong the line 2-2 in Figure 1,

Figure 3 is a diagram showing a proposed volume con-' trol for the sameapparatus, and

Figure 4 is a modification of an embodiment of the apparatus in Figure1.

Figure 1 shows the novel apparatus wherein the numeral 11 generallydesignates a shell defining a vortex chamber. The upper part of theseparator is provided with a tight cover 12, the lower part with aconically shaped bottom 13. The cover 12 supports a flange 14, wherein afeeding tube 15 can slide in an axial direction, this movement beingcontrolled by any suitable conven-' tional means, as for example atoothed gear 16. The tube 15 terminates downwardly by a discharge nozzle17, and is provided with spin imparting vanes 18, of any conventionaltype known. A horizontal feeding pipe 19 sup plies a carrier fluid by atangential inlet 20 into the upper part of the vortex chamber 21. On thebottom 13, a series of intercepting partition sleeves 22, 23 and 24 arefixed concentrically below the discharge nozzle 17. The sleeve 22 isplaced centrally in the axial path of said nozzle 17; the sleeves 23 and24 are placed concentrically in a downwardly sloping sequence around thesleeve 22, forming the annular spaces 23, 24' and that one" marked bynumeral 25, between the sleeve 24 and the shell 11. The primaryseparation takes place on their edges which define the primaryseparation area. After the primary separation, the fractions of thesuspension, spinning within the annular spaces 23, 24' and 25, aresubject to a further density stratification and are separated inthe'secondary separation areas which are defined by the edges of shortersleeves 26, 27 and 28, placed inside the annular spaces 23, 24 and 25respectively. A tertiary separation area is provided in the annularspace 24, by the very short sleeve 29. The inner space of the sleeve 22and all the annular spaces are provided each with an outlet draining therespective separation area; these outlets are marked by numerals 30 to37 respectively. All of the annular spaces are further provided withdrain regulating covers 3 8,fixed at a small distance from the bottom13. The

' covers 38 are shown in plan view in Figure 2 in their operativepositions. Each cover 38 is a large washer of a thin material as sheetmetal, fitting exactly in its an nular space and provided with a seriesof openings 39, varying from relatively small to large incross-sectional area. The smallest opening is close to the outletdraining the area; for instance, the cover 38 in the annular space 25,between the shell 11 and the sleeve 28, has its smallest opening 39close to the outlet 37, the largest opening 39 being on the oppositeside of the circumference of the same cover. The volume of flow passingthrough the largest opening 39 must travel the longest distance to reachthe outlet 37. The shorter the distance for the fiuid to reach theoutlet 37, the smaller the opening 39, so that the fluid passing throughany one of the openings 39 has to overcome the same resistance.Therefore, equal volumes of fluid will pass through each opening 39,whatever its size. In this manner, the spinning fluid will be drainedevenly along the whole circumference of each annular space, thusavoiding any turbulence in the adjacent separation areas. Thethroughflow in outlets 30 to 37 is controlled by variable valves of anywell known type.

-In operation, two differentflows are fed into the ap-' paratus. Thecarrier fluid is supplied by the feed pipe traveling on a helical pathof the vortex-chamber 21 iron the inlet 20, is spread in said spinningcarrier in the form of a truncated cone S. Particles heavier than thecarrier are driven outwardly in a radial direction by centrifugalaction. In this radial travel, the heavier particle works its way fasterthan the lighter one. All the particles being of the same size, it isthe density which will determine for each of them the velocity of theradial escape. By the time the spreadingmass of fine solids reaches theprimary separation area, a clear density spectrum is formed on the baseof the cone S. The height of this cone will depend upon the twocomponents of the helical movement of the carrier fluid, and thespreading of the fine solids which is represented by the base of thecone should cover the whole primary separation area. The distance of thenozzle 17 from the primary separation area being variable, the optimumposition of the nozzle 17 will be found by sliding the feeding tube 15in an axial direction, with a simultaneous actuating of variable valvesin the outlet passages. Thus, the spreading mass meets, in its axialtravel, the edges of the primary separation sleeves 22, 23 and 24, asshown in Figure 1, when the heaviest particles are approaching theperiphery of the chamber 21, while the lightest ones stay close to theaxis thereof. The stmtified suspension is split by said edges intoconcentric cylinders, yielding fractions of fluid carrying fine solidswith densities ranging as in said density spectrum. The spin offractions in annular spaces 23, 24 and 25 continues whereby a furtherStratification is achieved within the spaces, and the suspension is thusseparated again on the edges of the secondary separation areas. A thirdseparation follows in the same manner in the tertiary separation area bythe sleeve 29, as explained above, and the partial flows are thenevacuated by the outlets 36 to 37. As a result, numerals 32, 34, 35 and37 yield fine solids in a state of thickened suspension, outlets 39, 31and 36 yield the surplus carrier fluid.

As stated above, the covers 38 provide for a uniform draining along thecircumference of each space. The use of said covers may be avoidedeither by providing each annular space with several outlet openingsequally spaced on the bottom, or by extending said spaces so as to decrease the velocity of the flow before it reaches the outlet.

When the passages of central outlets 30 and 31 drain the large part ofthe carrier fluid, they promote a lateral inward flow of the spinningfluid toward the center of the chamber 21. When this way of draining isused in a vortex chamber of a certain height, wherein the distance ofthe tangential inlet 20 from the intercepting sleeves 22 and 23 islarge, the helical fluid flow will tend to rotate rather in the centerof the chamber 21, cutting short its way towards sleeves 22 and 23, theremote peripheral layers will be idle, thus producing little or nolateral inward flow. This condition may be corrected by installing inthe chamber 21, one or more feeding sleeves 40, marked in dotted lines.The spinning carrier directed by the lower edges of these sleeves 40will exert a lateral pressure at any desired height onto the conicallyoutstretched fine solids material, and all layers will re tate.

The volume of fluid passing through the outlets 30- to 37 is controlledin order to obtain the maximum efficiency of separation in the annularspaces. Many conventional devices may be used for this purpose. Figure 3shows diagrammatically, by way of example, one possible solution forcontrolling the secondary and tertiary separations as those, forinstance, in the annular spaces 23 and 24. In Figure 3, the outlets 41and 43 evacuate fine solids, the outlet 42 evacuates the clean carrierfluid. The outlet numeral 43' which may or may not exist, is anauxiliary outlet for illustration purposes only. Baffles 44, 45, 46 and4d are pivotally mounted in the walls of outlets 41, 42, 43 and 43; thelever arms 47 forming one piece with the bafiies and with the journals48 will move said battles. The control of the flow through the outlets41 and 42 is regulated by a triangular guide 49. One side of this guide49 actuates, through the lever arm 47, making sliding contact therewithas a follower, the baffle 44 in the outlet 41, the other side of thesame guide actuates the baffle in the outlet 42. A similar triangularguide 49 makes sliding contact with the baffles 46 and 46 in the outlets43 and 43'. The triangular guides 49 are coupled by a bar 50 which issupported in its center by a fulcrum 51. This fulcrum may be movedhorizontally a short distance; it also allows a slight pivoting movementof the two guides 49, so that a vertical movement of one of them in onedirection causes the other guide to move in the opposite direction. Whenthe fulcrum 51 moves horizontally to the right, the volume of flowdrained by the outlets 41 and 43 will be increased, and that drained bythe outlets 42 and 43', if any, will be decreased to the same extent.The same movement to the left will reverse the effect in the sameoutlets. An upward movement of the guide 49 on the left hand side, willincrease the volume drained by the two outlets 41 and 42, to the sameextent in each member of this couple, while simultaneously the guide onthe right hand side will cause a reduction of the volume drained by theoutlets 43 and 43', also to the same extent in each member of thecouple.

Considering now the two outlets 41 and 42 belonging to the same primaryseparation area, a horizontal movement of the guide 49 between them willchange the ratio of the throughflows in the two secondary separationspaces drained by said outlets, while nothing is changed in the involvedprimary separation area. However, when the sarne guide 49 movesvertically, the throughflows in the same outlets are either increased ordecreased to the same extent, and such a change finds its expression inthe primary separation area in a changed volume and density of the fluidpassing therethrough. When a tertiary separation is operated andcont-rolled in a depending relation with the secondary ones performed inthe same line, a third outlet, either numeral 43 or 43, is connected bythe bar 51 to the couple 41, 42, or even both of them at the same time,in which case two pairs of outlets may vary the throughfiow volumes inthe respective sewndary and tertiary separation areas, while nothing ischanged in the remaining separation areas of the same unit. It will benoted that the connections shown in Figure 3 are only illustrative andthe possible combinations far too numerous to be mentioned here.Generally, any particular problem of the kind can find a suitablesolution.

The viscosity of the carrier fluid is a constant obstacle to a lateralpenetration, and is that factor which makes, in this method, densityseparations possible. In precision work, it is necessary that allparticles leaving the nozzle 17, start their spinning motion at the verymoment of discharge, if they are to be correctly separated. Thisrequirement is not always met in a single discharge nozzle 17, as shownin Figure 1, wherein the flow leaving said nozzle forms a solid cylindercontaining the axis of the spin. There is little or no radius ofrotation in this cylinder axis, thus, there is little or no centrifugaltension to move the particles radially into the spinning fluid. As saidcylinder disintegrates progressively in the nearby spinning carrier, asmall cone of the handled material projects downwardly from thedischarge nozzle 17, and will be spread out later than the otherparticles discharged at the same time from the same nozzle 17. In Figure4, a new feed tube 52 is shown which corrects this condition. The tube52 is provided with a core, concentric pipe 53, and the annular spacebetween them has spin imparting vanes 54, of any conventional type. Thepipe 53 has its own helix 55. A fine solid material discharged by thisdevice, will leave by said annular space, and all its particles willstart rotating instantly :as soon as discharged The effect may befurther as sisted by feeding a clean carrier fluid through the core pipe53. The spreading solids will form a layer, achieving a density spectrumat the base of the cone S, provided, the discharged particles have afairly uniform size. However, in the separation of materials in whichthe respective densities of the components are far apart from eachother, relatively large grain size diflerences are admissible.

The intercepting edge of sleeves 22, 23 and 24 may be at the same levelor in various positions, if desired. The friction in the partitionsleeves is reduced by their conical shape shown in Figure 1. At the sametime, the bottom space needed for connections is larger and helpful forslowing down the angular velocity of the partial flows before they areevacuated.

I claim:

1. An apparatus for multiple separation of suspended fine solidparticles from a mixture by density difference, comprising incombination: a closed vortex chamber having a substantially horizontaltop portion, a circular wall section and a bottom portion, tangentialfeeding means in said circular wall section enabling a carrier fluid tospin in said vortex chamber, separate feeding means for a mixture offine solid particles, arranged concentricall with said vortex chamberand substantially perpendicular to said tangential feeding means andmovable in an axial relation thereto, said separate feeding means beingopen in an axial direction to discharge said mixture axially so as tospread the same radially outwardly in a fine layer into said spinningcarrier, a first series of partition sleeves arranged concentricallyWithin said vortex chamber and providing primary annular spaces to splitinto fractions said carrier fluid with said particles suspended therein,a second series of partition sleeves arranged concentrically within saidprimary annular spaces and providing secondary annular spaces, anddraining means for each of said annular spaces.

2. Apparatus of claim 1 in which each of said annular spaces is providedwith an outlet and with drain regulating means having openings thereinin spaced relation along the circumference of each space and graduatedfrom small to large, each of said openings having a crosssection areathereof proportional to its distance from the outlet, to equalize theresistance to the throughflow in each of said openings.

3. Apparatus of claim 1 in which said separate feeding means consists ofa tube open in an axial direction into said vortex chamber and providedwith a core fixed concentrically in said tube, said core being a pipe ofsmaller diameter than said tube and having an open end substantially atthe same level with said tube open end, thus defining an annular spacein said tube open end, said annular space having fixed spin impartingmeans therein to impart a spin to said mixture of fine solid particlesand to discharge it in the form of a hollow cylinder in said carrierfluid substantially in an axial direction, said core dischargingsimultaneously another fluid flow in an axial direction.

References Cited in the file of this patent UNITED STATES PATENTS2,329,900 Hermann Sept. 21, 1943 2,726,765 Rakowsky Dec. 13, 19552,729,330 Newirth Jan. 3, 1956 2,762,656 Frazer Sept. 11, 1956 2,769,546Fontein Nov. 6, 1956 2,776,053 Krebs Jan. 1, 1957 2,783,887 ChisholmMar. 5, 1957 2,843,265 Rakowsky July 15, 1958 FOREIGN PATENTS 489,426Italy Ian. 22, 1954 538,448 Canada Mar. 19, 1957 862,599 Germany Jan.12, 1953

